.border(@width:1px, @color: #ccc, @style: solid){
  border-width: @width;
  border-color: @color;
  border-style: @style;
}
.btr(@len, @color){
    width:0;
    height:0;       
    .border(
      @len @len 0,
      @color transparent transparent transparent,
      solid
    );
    content: "";
    display: inline-block;     
}
.ltr(@len: 10px , @color: lightblue){
    width:0;
    height:0;       
    .border(
      @len @len @len 0,
      transparent @color transparent transparent,
      solid
    )  
}
.ttri(@len, @color){
    width:0;
    height:0;       
    .border(
      0 @len @len,
      transparent transparent @color transparent,
      solid
    );
    content: "";
    display: inline-block;     
}